Update README.md (#17)

README.md

@@ -1,5 +1,24 @@
 # calens
 
-This program is a changelog generator that nicely prints a changelog file from
+`calens` is a changelog generator that nicely prints a changelog file from
 a directory with versioned subdirs containing files. A sample directory can be
 seen in [the restic repository](https://github.com/restic/restic/tree/master/changelog)
+
+# Installation
+
+To install and run calens locally, run the following commands:
+```
+git clone https://github.com/restic/calens.git 
+cd calens
+CGO_ENABLED=0 go install
+```
+
+# Creating a Changelog
+
+To create a changlog.md file using calens, change into a repository containing a `changelog`
+folder similar to that of [restic](https://github.com/restic/restic/tree/master/changelog).
+Then run `calens -o changlog.md` from within the repository.
+
+When done, open the created changelog to see the generated changelog.
+
+Run `calens --help` for more options.